An ambitious sly snarky person who wishes to become Montagues heir. He is contemptuous of the common people and is charged by Montague to spy on Romeo. He also seems to have some degree of interest in Hermione but whether he has honest feelings for her or desires to use her as a pawn in his possible plans remains debatable. Mercutios desire for power appears to stem from his resentment towards his father Titus who doesnt live up to his sons expectations as a Montague advisor. Montague is aware of his disdain for his father and encourages none too subtlety Mercutio to kill Titus but he doesnt do it. A few days after Romeos banishment Mercutio agrees to be adopted as Montagues new heir but is unprepared for the bloody initiation whose climax was Titus death at the hands of Montague. Paralyzed by fear Mercutio could not voice out for help nor assist his fathers peril and later swore his loyalty to the bloodied Montague. He tries to fit the mold of Montagues heir but in truth the event of his fathers death has traumatized him and his guilt over doing nothing envelopes him. The obvious collapse of Montagues reign drives him to do what he thinks will get him the most praise: he stabs Montague and saves Juliet. Expecting to be called a hero he is stricken when Tybalt dismisses him and leaves from the scene in mad laughter. Souce: Wikipedia